This invention relates to novel compounds for use as steroid sulphatase inhibitors, and pharmaceutical compositions containing them.
Steroid precursors, or pro-hormones, having a sulphate group in the 3-position of the steroid nucleus, referred to hereinafter simply as steroid sulphates, are known to play an important part as intermediates in steroid metabolism in the human body. Oestrone sulphate and dehydroepiandrosterone (DHA) sulphate, for example, are known to play an important role as intermediates in the production, in the body, of oestrogens such as oestrone and oestradiol. Oestrone sulphate, in particular, is known, for example, to represent one of the major circulating oestrogen precursors particularly in post-menopausal women and oestrone sulphatase activity in breast tumours is 100-1000 fold greater than that of other enzymes involved in oestrogen formation (James et al., Steroids, 50, 269-279 (1987)).
Not only that, but oestrogens such as oestrone and oestradiol, particularly the over-production thereof, are strongly implicated in malignant conditions, such as breast cancer, see Breast Cancer, Treatment and Prognosis: Ed. R. A. Stoll, pp. 156-172, Blackwell Scientific Publications (1986), and the control of oestrogen production is the specific target of many anti-cancer therapies, both chemotherapy and surgical, e.g. oxc3x6phorectomy and adrenalectomy. So far as endocrine therapy is concerned, efforts have so far tended to concentrate on aromatase inhibitors, i.e. compounds which inhibit aromatase activity, which activity is involved, as the accompanying oestrogen metabolic flow diagram (FIG. 1) shows, in the conversion of androgens such as androstenedione and testosterone to oestrone and oestradiol respectively.
In recently published International Application WO91/13083 a proposal has been made to target a different point in the oestrogen metabolic pathway, or rather two different points, that is to say the conversion of DHA sulphate and oestrone sulphate to DHA and oestrone, respectively, by steroid sulphatase activity, and using 3-monoalkylthiophosphonate steroid esters as a steroid sulphatase inhibitor, more especially oestrone-3-monomethyl-thiophosphonate.
A first object of the present invention is to provide new compounds capable of inhibiting steroid sulphatase activity in vitro and in vivo.
A second object of the present invention is to provide new compounds having improved activity as steroid sulphatase inhibitors both in vitro and in vivo.
A third object of the invention is to provide pharmaceutical compositions effective in the treatment of oestrogen dependent tumours.
A fourth object of the invention is to provide pharmaceutical compositions effective in the treatment of breast cancer.
A fifth object of the invention is to provide a method for the treatment of oestrogen dependent tumours in mammals, especially humans.
A sixth object of the invention is to provide a method for the treatment of breast cancer in mammals and especially in women.
The invention is based on the discovery of novel compounds having steroid sulphatase inhibitory activity, in some cases, with extremely high activity levels.
In one aspect, the present invention provides a method of inhibiting steroid sulphatase activity in a subject in need of same.
In another aspect, the present invention provides compounds and compositions useful in that method of inhibiting steroid sulphatase activity.
The method of the present invention comprises administering to said subject a steroid sulphatase inhibiting amount of a ring system compound; which ring system compound comprises a ring to which is attached a sulphamate group of the formula 
wherein each of R1 and R2 is independently selected from H, alkyl, alkenyl, cycloalkyl and aryl, or together represent alkylene optionally containing one or more hetero atoms or groups in the alkylene chain, and wherein said compound is an inhibitor of an enzyme having steroid sulphatase activity E.C.3.1.6.2); and if the sulphamate group of said compound is replaced with a sulphate group to form a sulphate compound and incubated with a steroid sulphatase enzyme (E.C.3.1.6.2) at a pH 7.4 and 37xc2x0 C. it would provide a Km value of less than 50 xcexcM.
The compounds that are useful in the method of the present invention are sulphamic acid ester ring system compounds, the sulphate of which is a substrate for enzymes having steroid sulphatase (EC 3.1.6.2) activity, the N-allyl and N-aryl derivatives of those sulphamic acid esters, and their pharmaceutically acceptable salts.
In one aspect of the present invention, compounds for use in the method of the present invention are the sulphamic acid esters of polycyclic alcohols, being polycyclic alcohols the sulphate of which is a substrate for enzymes having steroid sulphatase (EC 3.1.6.2) activity, the N-alkyl and N-aryl derivatives of those sulphamic acid esters, and their pharmaceutically acceptable salts.
For one aspect of the present invention, broadly speaking, the novel compounds of this invention are compounds of the Formula (I) 
where:
R1 and R2 are each independently selected from H, alkyl, cycloalkyl, alkenyl and aryl, or together represent alkylene optionally containing one or more hetero atoms or groups in the alkylene chain; and
the group xe2x80x94O-Polycycle represents the residue of a polycyclic alcohol, the sulphate of which is a substrate for enzymes having steroid sulphatase activity (EC 3.1.6.2).
As used herein the reference to polycyclic alcohols, the sulphate of which is a substrate for enzymes having steroid sulphatase activity refers to polycyclic alcohols, the sulphate of which, viz: the derivatives of the Formula: 
when incubated with steroid sulphatase EC 3.1.6.2 at pH 7.4 and 37xc2x0 C. provides a Km value of less than 50 xcexcmoles.